JPH07118301A - Microbial cellulose dispersion - Google Patents

Abstract

PURPOSE:To obtain a dispersion having higher paper-strengthening effect than that of the conventional dispersion by physically dispersing a microbial cellulose so that the average FL value and/or the value of sedimentation compression degree of the dispersion falls within a specified range. CONSTITUTION:The dispersion is obtd. by obtd. by physically dispersing a microbially produced cellulose and has an average FL value at least equal to or higher than that of the cellulose before dispersed and a degree of sedimentation compression of 0.27-0.37. Although the dispersion having either the average FL value or the degree of sedimentation compression in the above-mentioned range can fulfil the purpose, the one satisfying both conditions is more pref. The dispersion pref. has 1.5-1.7 times, 1.6-2.2 times and 1.5-1.9 times of the number-average FL value, length-weifgted-average FL value and wt.-weighted- average FL value of the cellulose before dispersed respectively. The cellulose is dispersed pref. with an ultrasonic crusher.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dispersion of cellulose produced by a microorganism. More specifically, it relates to a dispersion of microbial cellulose having an excellent paper-strengthening effect.

[0002]

Many applications have been proposed for microbial cellulose. For example, as described in JP-A-62-36467, it is used for papermaking for the purpose of increasing paper strength. Further, it is used as a stabilizer for solid foods as described in, for example, JP-A-62-294047.

Microbial cellulose is in a state in which microfibrils of cellulose are intricately entangled with each other when it is cultured and produced. A microbial cellulose dispersion is obtained by individually separating and dispersing entangled cellulose microfibrils.

[0004] Conventionally, microbial cellulose produced by culturing has been made into a dispersion by applying mechanical shearing force with a mixer or the like. For example, JP-A-61-113
Japanese Patent No. 601 describes that a gel-like cellulosic substance produced by a microorganism is dispersed by applying a mechanical shearing force. It has been shown that mechanical shearing can be carried out specifically using rotary disintegrators, mixers and homogenizers. The microbial cellulose dispersion obtained by this dispersion method has excellent aqueous dispersibility and water retention. Japanese Unexamined Patent Publication No. 5-51885 describes a method of dispersing bacterial cellulose in a dry state by applying high-speed shearing force. High speed shear, rotary mixer,
It has been shown that it can be carried out by a device such as a homogenizer or a homomixer, and can also be used in combination with a device such as a high pressure homogenizer, a beater, a double disc refiner or Jordan.

[0005]

When microbial cellulose is used for papermaking, microbial cellulose is more expensive than plant cellulose. Therefore, it is possible to obtain a sufficient paper-strengthening effect by using a smaller amount of microbial cellulose. It has been demanded.

Accordingly, it is an object of the present invention to obtain a microbial cellulose dispersion suitable for papermaking, in which the paper-strengthening effect of the microbial cellulose dispersion is further improved as compared with conventional microbial cellulose dispersions.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies to achieve the above object. As a result, they have found that there is a close relationship between the average FL value or sedimentation compression degree (the definition etc. will be described later) of the microbial cellulose dispersion and the paper strength of the produced paper, and have completed the present invention. It was

That is, the present invention is a cellulose dispersion obtained by physically treating cellulose produced by a microorganism, wherein the average F of cellulose before the dispersion treatment is obtained.
Dispersions characterized by having an average FL value which is greater than or equal to the L value.

Average FL of microbial cellulose before dispersion treatment
If the average FL value of the microbial cellulose dispersion is smaller than the value, drainage in the papermaking process is deteriorated.

The average FL value in the present invention is a value measured by the method described below, and is considered to reflect the size of the aggregate of microbial cellulose. However, other methods such as electric resistance method [measurement method using Coulter counter (trade name)], sedimentation method, density gradient centrifugation method,
It can be measured by a light scattering method, an ultrasonic scattering method, an observation under an optical microscope or an electron microscope, an image processing method, a sieving method, a surface area measuring method, an optical path shielding method and the like.

The microbial cellulose-water suspension was added to Kajaa.
ni Fiber length distribution measuring device FS-200 (Kajaani
(Manufactured by Oy Electronics), and each average FL value is determined as the average value of the measured values in the range of 0 to 1.75 mm.

The microbial cellulose before dispersion treatment exists in a state in which microfibers are entangled (fiber aggregate), and when dispersed, the average FL value apparently changes. Although each average FL value of the microbial cellulose dispersion according to the conventional method is smaller than each average FL value of the microbial cellulose before the dispersion treatment, each average FL value of the microbial cellulose dispersion of the present invention is equal to each of the microbial cellulose before the dispersion treatment. It is characterized by having each average FL value that is greater than or equal to the average FL value. That is, the microbial cellulose dispersion of the present invention is obtained by the dispersion operation in which the effect of disentangling the fibers of the microbial cellulose is greater than the effect of breaking or cutting the fibers or fiber aggregates of the microbial cellulose.

1.5 to 1.7 relative to cellulose before dispersion
Double number average FL value, 1.6-2.2 times length weighted average F
Microbial cellulose dispersions having L values and weight-weighted average FL values of 1.5 to 1.9 times are preferred. If each average FL value is larger than the above value, the texture of the paper sheet is deteriorated when manufactured, and the strength of the sheet is lowered.

The average FL value of the particularly preferred microbial cellulose dispersion has a number average FL value of 0.28 to 0.32 mm, a length weighted average FL value of 0.55 to 0.74 mm, and a weight weighted average FL value of 0. It is 0.84 to 1.04 mm.

If each average FL value is larger than each of the above-mentioned values, the texture of the paper sheet is deteriorated and the strength of the sheet is deteriorated. It becomes worse and production efficiency is poor.

The present invention also has a sedimentation compressibility of 0.27 to
It also relates to a microbial cellulose dispersion characterized in that it is 0.37.

If the sedimentation compressibility is lower than the above value, the stability of the suspension of the microbial cellulose dispersion is deteriorated and the strength of the sheet is lowered, and if it is higher than the above value, the drainage is deteriorated. Occurs.

The object of the present invention can be achieved if the microbial cellulose dispersion of the present invention satisfies at least one of the above-mentioned average FL value and sedimentation compressibility, but it is more preferable that both conditions are satisfied at the same time.

The microbial cellulose in the present invention can be obtained by static culture, stirring culture, aeration culture, shaking culture, or a combination thereof. For example, JP-A-59-
120159, JP 61-152296, JP 61-212295, and JP 62-2.
65990, JP-A-62-175190,
JP-A-63-202394, JP-A-62-364
67, Japanese Patent Laid-Open No. 63-74490, Japanese Patent Publication No.
It can be obtained by the method described in JP-A-500116, JP-B-62-500630 and the like. Microbial cellulose obtained by stirring culture, aeration culture, and shaking culture, particularly preferably aeration stirring culture.

The sedimentation compressibility in the present invention is measured by the following method. 0.1% (microbial cellulose dry weight / volume)
Of the microbial cellulose-water suspension of
~ 15 ml is weighed into a centrifuge-capable test tube (internal diameter 14 mm x length 120 mm, volume 15 ml). The test tube is centrifuged at 3000 rpm (about 1700 x G) for 30 minutes to precipitate microbial cellulose. The ratio of the volume (v) occupied by the precipitated microbial cellulose after the end of centrifugation to the volume (V) of the suspension, that is, v / V, is calculated,
Sedimentation compressibility.

The microbial cellulose in the present invention may be cultivated together with other fibrous substances such as pulp, organic synthetic fibers and inorganic synthetic fibers, inorganic fillers, whiskers and the like.

The microbial cellulose may be chemically modified such as methylated or acetylated.

Dispersion of microbial cellulose is considered to be caused by mechanical external force that causes stress inside the cellulose to be deformed and destroyed. Mechanical external forces include tension, bending, compression, twisting, impact, shearing, etc., but generally compression, impact, shearing are the main components.

In the dispersion by the mixer, the mechanical external force mainly consists of the impact force caused by the collision of the stirring blade and the microbial cellulose, and the shear stress generated by the displacement phenomenon due to the speed difference of the medium.

In the dispersion by polytron, the mechanical external force is the compressive force due to the microbial cellulose being sandwiched between the outer tooth and the inner tooth, the impact force due to the collision between the tooth rotating at high speed and the microbial cellulose, and the stationary outer tooth. The shear stress generated in the medium existing in the gap between the inner teeth rotating at high speed is the main factor.

In the dispersion by the ultrasonic crusher, the mechanical external force mainly consists of remarkable shear stress which is locally generated by cavitation (cavity phenomenon) in the medium due to the oscillation of the ultrasonic oscillator.

As described above, the microbial cellulose dispersion of the present invention can be obtained by a dispersing operation that has a greater effect of loosening the entanglement of fibers than the effect of breaking or cutting the fibers or fiber aggregates of microbial cellulose.

The microbial cellulose dispersion of the present invention can be produced, for example, by the following method. Microbial cellulose obtained by culturing is separated from the culture broth by centrifugation or filtration. The separated microbial cellulose is washed if necessary.
Washing can be performed with water or an aqueous solution of an acid, an alkali, a neutral detergent, a surfactant, a bleaching agent or the like. Then, water, a solvent and the like are added to adjust the dispersion concentration, and then the suspension is dispersed by applying a physical force. As a device for applying a physical force, any device can be used as long as it can obtain the average FL value and / or the compression sedimentation degree of the microbial cellulose described above. Examples thereof include a mixer, a homogenizer, a homomixer, a polytron (trade name), and an ultrasonic crusher. These devices may be used in combination. A preferred device is an ultrasonic disintegrator. By adjusting the degree of dispersion, the average FL value and / or the degree of sedimentation compression of the microbial cellulose dispersion can be brought into the above range. The degree of dispersion can be adjusted, for example, by changing the output of the device or changing the dispersion time.

Dispersions include water, an electrolyte such as calcium chloride and sodium chloride in a solvent, a pigment, an inorganic compound such as activated carbon fine particles, a sizing agent, a yield improving agent, a fluorescent agent, an antifungal agent,
An organic compound such as an antistatic agent or latex may be mixed in advance.

[0030]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the examples are not intended to limit the present invention.

Examples and Comparative Examples Culture Conditions for Microbial Cellulose Cellulose-producing acetic acid bacteria were cultured using a flask culture method and a jar fermenter culture method.

Microbial Cellulose Flask Culture Method 40 g / L Fructose, 1.0 g Monopotassium Phosphate /
L, magnesium sulfate 0.3 g / L, ammonium sulfate 3 g / L, bacto-peptone 5 g / L, lactic acid 1.4 ml
Cellulose-producing acetic acid bacterium Acetobacter species BPR200 in a 750 ml Roux flask containing 100 ml of basic medium having a composition of / L and initial pH of 5.0.
1 (FERM P13466) of a cryopreserved bacterial solution was inoculated and statically cultivated in a constant temperature incubator at 28 ° C. for 3 days. After the seed culture, the Roux flask was shaken well, and the contents were gauze-filtered under aseptic conditions to separate the cellulose pieces and the bacterial cells. Then 15 at 10,000 rpm
Centrifuge for minutes, medium components and cells (+ microcellulose)
The cells were separated, and the bacterial cells (+ microcellulose) were washed once or twice with sterile physiological saline, and centrifugation was repeated. A required amount of sterile physiological saline was added to the washed bacterial cells, and after stirring, this was used as a seed bacterial solution.

Next, 7.5 ml of the seed bacterial solution was inoculated into a 300 ml baffle flask containing 67.5 ml of the above basic medium. Using a shaking culture machine, cultivation was performed for 4 days while rotating and shaking under conditions of an amplitude of 2 cm, a rotation speed of 180 rpm, and a temperature of 28 ° C. The solid matter in the flask was washed with water to remove the medium components, and then 110% in 1% NaOH aqueous solution.
The cells were treated at 20 ° C. for 20 minutes to remove the cells, and the cellulose was washed with water until the washing solution became nearly neutral to obtain microbial cellulose. This microbial cellulose was used for experiments such as dispersion.

Jar fermenter culturing method of microbial cellulose Ro in 750 ml containing 100 ml of the above basic medium
The cellulose-producing acetic acid bacterium Acetobacter species BPR2001 (FERM P1346) was added to the ux flask.
1 ml of the cryopreserved bacterial solution of 6) was inoculated, and 2
Static culture was performed at 8 ° C for 3 days. After the stationary culture was completed, the Roux flask was shaken well, and then the contents were subjected to gauze filtration under aseptic conditions to separate cellulose pieces and cells. 7.5 ml of the obtained bacterial solution was inoculated into a 300 ml baffle flask in which 67.5 ml of the above-mentioned basic medium was placed, and shake-rotated using a shaking incubator under the conditions of an amplitude of 2 cm, a rotation speed of 180 rpm and a temperature of 28 ° C. While performing seed culture for 3 days.

After completion of the culture, the content of the flask was used as a seed bacterial solution and used for the following jar fermenter culture.

A small jar fermenter (total volume of 1000) in which 60 ml of the above seed bacterial solution was sterilized and 540 ml of the medium for culturing the jar fermenter described later was put into
ml) and aseptically inoculated at 30 ° C. for 20 or 30 hours at pH of 1N NaOH or 1N H ₂ SO ₄ .
While controlling to 0, the stirring rotation speed was initially 4
At 00 rpm, the dissolved oxygen content (DO) is 3.0 to 21.0
The culture was performed with a jar fermenter while automatically controlling the number of rotations so as to be within%.

For the jar fermenter culture, a medium having the following composition was used.

Fructose 40 g / L, KH ₂ PO ₄ 1.0 g / L, MgSO ₄ 0.3 g / L, (NH ₄ ) ₂ SO ₄ 3 g / L, Bacto-Soyton (manufactured by Difco) 5 g / L and beans Concentrate (acid hydrolyzed concentrate of soybean protein) 5 g / L Initial pH 5.0 After completion of the culture, the solid matter in the jar fermenter is collected, washed with water to remove the medium components, and then in a 1% NaOH aqueous solution. The cells were removed by treatment at 110 ° C. for 20 minutes. Further, the produced cellulose was washed with water until the washing liquid became nearly neutral, and then used for experiments such as dispersion.

Dispersion of Microbial Cellulose Water was added to the washed microbial cellulose obtained by the above flask culture method or jar fermenter culture method to adjust the dispersion concentration to 0.1% (dry weight / volume of microbial cellulose). Then, this suspension was dispersed by an ultrasonic disintegrator at 25 ° C. for 3 minutes. Average F of the obtained dispersion and undispersed product
The L value and the degree of sedimentation compression were measured.

For comparison, a suspension prepared by adding water to the washed microbial cellulose obtained by the above flask culture method or jar fermenter culture method to adjust the dispersion concentration to 0.1% (dry weight / volume of microbial cellulose). Was dispersed by a conventional method (using a mixer) at 25 ° C. for 1 minute. The average FL value and sedimentation compression degree of the obtained dispersion were measured.

The above series of operations including the culturing step were repeated 10 times. The measurement results are shown in Table 1.

[0042]

[Table 1]

The measured value shows the average value of the values measured 10 times, and the value in parentheses shows the range of the value measured 10 times.

Preparation of Paper Containing Microbial Cellulose: Dispersed or Undispersed Microbial Cellulose and JIS-P-8
209 disintegrated LBKP with respect to 100 parts of pulp in which a dry solids weight ratio of 40:60 was mixed,
100 parts of light calcium carbonate and 1 part of positive starch were added, and the basis weight was 100 g / m ² with a standard handmade sheet machine.
Paper was made.

Breaking length The breaking length of the microbial cellulose-containing paper prepared above was measured by JI
It was measured in accordance with SP-8113 and used as an index of the paper strength enhancing effect.

Table 2 shows the breaking length.

[0047]

[Table 2]

The measured value shows the average value of the values measured 10 times.

[0049]

INDUSTRIAL APPLICABILITY The microbial cellulose dispersion of the present invention can greatly improve the paper strength enhancing effect as compared with conventional dispersions.

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[Procedure amendment]

[Submission date] December 6, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

The microbial cellulose dispersion of the present invention can be produced, for example, by the following method. Microbial cellulose obtained by culturing is separated from the culture broth by centrifugation or filtration. The separated microbial cellulose is washed if necessary.
Washing can be performed with water or an aqueous solution of an acid, an alkali, a neutral detergent, a surfactant, a bleaching agent or the like. Then, water, a solvent and the like are added to adjust the dispersion concentration, and then the suspension is dispersed by applying a physical force. As a device for applying a physical force, any device can be used as long as it can obtain the average FL value and / or the compression sedimentation degree of the microbial cellulose described above. Examples thereof include a mixer, a homogenizer, a homomixer, a polytron (trade name), and an ultrasonic crusher. These devices may be used in combination. In addition, these devices
Of these, the preferred device is an ultrasonic crusher. Microbial cell
If lulose is suspended in a medium and dispersed by a crusher, crush it.
The shearing stress generated by the machine in the medium becomes the driving force for dispersion.
It However, in a normal shredder, turbulence of the medium is generated at the same time.
Microbial cellulosic fibers become entangled and disperse
It becomes an obstacle. Therefore, the most turbulent flow of media in the crusher
Ultrasonic destroyer, which is rare, is effective as a disperser
Because it is considered. By adjusting the degree of dispersion, the average FL value and / or the degree of sedimentation compression of the microbial cellulose dispersion can be brought into the above range. The degree of dispersion can be adjusted, for example, by changing the output of the device or changing the dispersion time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location (C12P 19/04 C12R 1:02)

Claims (9)

[Claims] 1. A cellulose dispersion obtained by physically treating cellulose produced by a microorganism, which has an average FL value which is greater than or equal to the average FL value of the cellulose before the dispersion treatment. And the dispersion. 2. From 1.5 to the cellulose before the dispersion treatment.
A number average FL value of 1.7 times, a length weighted average FL value of 1.6 to 2.2 times, and a weight weighted average FL value of 1.5 to 1.9 times. 1. The cellulose dispersion according to 1. 3. A cellulose dispersion obtained by physically treating cellulose produced by a microorganism, wherein the degree of sedimentation compression is 0.27 to 0.37. 4. The cellulose dispersion according to claim 3, having an average FL value that is greater than or equal to the average FL value of the cellulose before the dispersion treatment. 5. From 1.5 to the cellulose before dispersion treatment
A number average FL value of 1.7 times, a length weighted average FL value of 1.6 to 2.2 times, and a weight weighted average FL value of 1.5 to 1.9 times. The cellulose dispersion according to item 3. 6. A cellulose dispersion obtained by physically treating cellulose produced by a microorganism, having a number average FL value of 0.28 to 0.32 mm and a length weighted average FL value of 0.55. ~ 0.74mm, weighted average F
A cellulose dispersion having an L value of 0.84 to 1.04 mm. 7. The cellulose dispersion according to claim 6, having an average FL value that is greater than or equal to the average FL value of the cellulose before the dispersion treatment. 8. From 1.5 to the cellulose before the dispersion treatment.
A number average FL value of 1.7 times, a length weighted average FL value of 1.6 to 2.2 times, and a weight weighted average FL value of 1.5 to 1.9 times. 7. The cellulose dispersion according to item 6. 9. The cellulose dispersion according to claim 6, which has a degree of sedimentation compression of 0.27 to 0.37.